Southern Stargazer

Astroscopus y-graecum

This unusual, stout fish has completely adapted to spending most of its life buried in sand, waiting to ambush its prey and gulp it down whole. Its eyes, gill slits, nostrils and most of its mouth are on the top of its body, and its pectoral fins are adept at digging and burying. It is a dark blackish-brown with white spots on head and body, and striped fins, and it can grow to almost 22 inches long. There is a special organ just behind its eyes that produces an electric shock which it uses defensively, so caution is advised when handling this fish.

Order – Perciformes
Family – Uranoscopidae
Genus – Astroscopus
Species – y-graecum

Common Names

Southern stargazer (English), aniquim (Portuguese), miracielo pintado (Spanish), and uranoscope tachete (French) are common names used to refer to Astroscopus y-graecum.

Importance to Humans

Because of the stargazer’s ability to produce electrical currents, live specimens of this species should be handled with care. If approached by a diver, it generally will not move unless disturbed.

Conservation

The southern stargazer is not listed as endangered or vulnerable with the World Conservation Union (IUCN). The IUCN is a global union of states, governmental agencies, and non-governmental organizations in a partnership that assesses the conservation status of species.

> Check the status of the southern stargazer at the IUCN website.

Geographical Distribution

The southern stargazer occurs in the western Atlantic Ocean from North Carolina (US) and the northern Gulf of Mexico, south to the northern coast of South America. It is absent in the West Indies.

Habitat

The southern stargazer, Astroscopus y-graecum, is a benthic species. It lives most of its life inshore, on or under sandy, silty, and rubble bottoms at depths to 230 feet (70m).

Biology

Distinctive Features
This fish has many adaptions to life under the sand. Its pectoral fins act as shovels, allowing the fish to bury in a matter of seconds. The body is designed so that the eyes, nostrils, and most of the mouth are above the sand when the fish is under the sand. Scales are absent on head, but are present on body, extending onto fleshy area of caudal fin. The eyes are capable of protruding for a short distance, appearing stalked, so that the stargazer can see above the sand. It brings in water through its nostrils to breathe. Most fish species bring in water through their mouths. The nostrils are protected from sand grains by fleshy, comb-shaped fringes. The mouth also has these fringes around it to keep sand out while the fish is buried. The gill slit is narrow and drawn backwards and upwards into a baggy tube. This tube carries waste water away from the fish and outside the surrounding sand. This fish possesses a special talent: it is able to create electrical currents from a specialized organ located in a pouch behind the eyes. The rate of electric discharge depends upon the temperature, with a maximum of 50 volts. It is used primarily to fend off aggressive, threatening fish rather than for prey capture.

Coloration
The southern stargazer has a blackish-brown body covered with white spots that gradually increase in size towards the rear of the body. White spots are widely spaced on the top of head and body. There are three dark, horizontal stripes on the tail. The northern stargazer, Astroscopus guttatus, closely resembles the southern stargazer in appearance and in life history. An easy way to tell these two species apart is to note the middle stripe on the tail. On the northern stargazer this stripe extends onto the rear portion of the body; on the southern stargazer this stripe does not extend pass the tail.

As a predatory species, the southern stargazer feeds on smaller fish that are unlucky enough to swim near it. Prey capture does not involve the electrical organ. Its main function is to protect the stargazer from anything that may threaten the fish. The stargazer instead relies on its camouflage and lies in wait for a small fish to swim near it. Once the prey is in range, the stargazer immediately rises from the sand and in an instant swallows the small fish whole.

Reproduction
The southern stargazer, true to its benthic nature, spawns on the bottom during the late spring and early summer months. The eggs are small, transparent, and slowly float to the surface. These eggs hatch into small, transparent larvae that live in the water column. These pelagic larvae grow rapidly, feeding off the yolk sac until they reach about 6-7mm in length. At this time the larvae begin feeding on other larvae in the water column, including some of their own kind. They also begin to acquire a black color that deepens in time. As they grow, a bright yellow spot appears on the chin. The electric organs begin to form when the larvae reach about 12-15mm in length. At this length the larvae head for the bottom and become a true juvenile. Juveniles tend to move inshore to sandy bays, where they may stay for several years. Here the juveniles will develop the characteristic patterns of the adults. The eyes, which were on the side of the larval head, will also migrate to the top of the head. When the juveniles reach about a foot in length, they move offshore and become adults.

Taxonomy

Uranoscopus y-graecum (Cuvier, 1829) was the original scientific name used to describe this fish, however it was later changed to the current name, Astroscopus y-graecum (Cuvier, 1829). From Latin, Astroscopus can be translated as “one who aims at the stars”.

Prepared by: Casey Patton